Theory of quadrupolar sunspots and the active region of August, 1972

@article{Yang1983TheoryOQ,
  title={Theory of quadrupolar sunspots and the active region of August, 1972},
  author={Hai-shou Yang and H. Chang and J. Harvey},
  journal={Solar Physics},
  year={1983},
  volume={84},
  pages={139-151}
}
Energy is stored when the force-free magnetic field in an active region departs from a potential field, the departure showing up as a shear in the field. As soon as the field untwists, energy will be released to produce flares. Based on this idea, we derived an analytical solution of the equation of force-free field under the assumption of a constant force-free factor, and found expressions for seven important quantities for quadrupolar sunspots: the magnetic energy of the twisted field, that… Expand
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References

SHOWING 1-10 OF 12 REFERENCES
A force-free field theory of solar flares: II. Bipolar sunspots
Based on the general solution of the force-free field obtained in Paper I, we give the corresponding expressions for a bipolar sunspot. The magnetic energy of the twisted field, that of the potentialExpand
Force-free magnetic fields and flares of August 1972
AbstractsOn the basis of observations (Zirin and Tanaka, 1973) inferring the presence of shear in magnetic fields, the amount of extractable energy stored in a class of force-free magnetic fields isExpand
On the magnetic field in pores
The magnetic field in an axisymmetric pore is current free and can be represented by a flux tube with a magnetic potential of the formAJ0(kr)e-kz. For a given magnetic flux the field in this poreExpand
Convection and magnetic fields in stars
Recent observations have demonstrated the unity of the study of stellar and solar magnetic fields. Results from numerical experiments on magnetoconvection are presented and used to discuss theExpand
On the topology of filaments and chromospheric fibrils near sunspots
The similarity between the spiral topology of chromospheric fibrils and filaments observed in Hα near sunspots and the configuration of an axisymmetric force-free magnetic field is examined. It isExpand
Morphological analysis of the large sunspot group of October 1972
1. 1. The main morphological feature of this proton active region is the clockwise spiral structure of the penumbral filaments of the large preceding spot “A”. 2. 2. The formation of this spiralExpand
Flares of August 1972: Analysis of dynamics
The optical observations and analyses of the flares of August 1972 are reviewed with emphasis on their dynamics. In particular, various assessments are made of possible quantitative interpretation ofExpand
Force-free magnetic fields in resistive magnetohydrostatics
Abstract It is proven that, in resistive magnetohydrostatics, the only force-free magnetic fields B which remain force-free in time are those for which α is constant in space and time, where α isExpand
Some supplementary analyses of a solar active region in August 1972
Abstract We have probably observed the phenomena of transfer of penumbral vortical pattern between two sunspots in a solar active region in August 1972. We compared our observations with those ZirinExpand
Solutions for Force-Free Magnetic Fields
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